How popular is Dianna?

Dianna is a very prominent first name for women (#418 out of 4276, Top 10%) and also a very prominent last name for both adults and children (#58849 out of 150436, Top 39%). (2000 U.S. Demographics)

Dianna entered the list in 1930-1939 and reached its top position of #208 in the U.S. in the 1950s, and is presently at #1801. (2015 U.S. SSA Records)

Which version is better?

with its source form and related girl names. Diana(#295 via latest list), Deanna(#1198), Dayanna(#1405), Diann, Dianne, Dyan, Dyanne, Dyann, Diane, Diandra, Deandra, Deann, Dena, Dian, Deana and Deane are the popular alternative forms of Dianna (#1801 via latest list) appearing in the Top 2000. Other variants, like Diahna, are seldom used. Usage of these forms of Dianna was widespread among parents in the 1950s (adoption of 1.9%) and has become much less since (adoption 0.1%, down 96%), with versions such as Dianne becoming somewhat outmoded.